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See detailFusion-based Additive Manufacturing for Processing Aluminum Alloys: State-of-the-Art and Challenges
Mertens, Anne ULiege; Delahaye, Jocelyn ULiege; Lecomte-Beckers, Jacqueline ULiege

in Advanced Engineering Materials (2017), 19(8), 1700003

Starting early 2015, the fusion-based additive manufacturing of Al alloys has been developing at an ever faster pace after undergoing a comparatively slow start with respect to other metallic materials ... [more ▼]

Starting early 2015, the fusion-based additive manufacturing of Al alloys has been developing at an ever faster pace after undergoing a comparatively slow start with respect to other metallic materials. This paper reviews the recent developments with the aim of identifying major challenges and opportunities for future work. Laser Beam Melting proves the most useful technique for the additive fabrication of Al components with strongly out-of-equilibrium microstructures and potentially enhanced mechanical behavior. Laser Cladding is also promising for specific applications such as repairs and coatings. However, a deeper understanding of the thermal history during fabrication is still needed to further optimize the microstructures and usage properties. The design of new high strength alloys and of Al-matrix composites, and the development of better adapted post-processing procedures to take greater advantage of the specificities of fusion-based additive techniques are two other important issues in view of reaching the full potential of additive Al components. [less ▲]

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See detailMultifunctional Polyelectrolytes Bearing Pendant Catechol / Quinone for Energy and Environmental Applications
Patil, Nagaraj ULiege

Doctoral thesis (2017)

The discovery of 3,4-dihydroxyphenyl-L-alanine (L-DOPA), a catechol-functionalized amino acid as major component in mussel adhesion proteins, has triggered enormous interest in mussel-mimetic adhesives ... [more ▼]

The discovery of 3,4-dihydroxyphenyl-L-alanine (L-DOPA), a catechol-functionalized amino acid as major component in mussel adhesion proteins, has triggered enormous interest in mussel-mimetic adhesives. The design of innovative bioinspired polymers-containing catechols has rapidly gained widespread utility in the (bio)material field, ascribed to the versatility of the catechol chemistry that allows anchoring (bio)polymers, biomolecules, nanoparticles (metals and metal oxides) and other compounds onto almost any kind of surfaces without any pre-treatment. Amongst the various synthetic protocols to incorporate catechol functionalities into (bio)polymers, the radical polymerization of catechol-bearing vinyl monomers in their protected form has proven to be a versatile technique to impart intrinsic physico–chemical properties of the catechol pendants to polymers after appropriate deprotection. Importantly, the scope of applications of catechol-bearing polymers can potentially be drastically increased by developing controlled radical polymerization (CRP) techniques of their protected vinyl monomers. Indeed, these techniques will enable to precisely design the polymer with the appropriate structure, molar mass and functionality that fit at best the target application. When this thesis started in 2013, only very limited examples of functional catechol-bearing polymers prepared by CRP were reported. The aim of this PhD thesis was to develop well-defined innovative catechol-containing (co)polymers that find applications in energy storage and environmental fields by employing function-oriented macromolecular engineering approaches. In this work, numerous catechol-protected monomers have been prepared and their CRP investigated to afford well-defined (co)polymers with controlled and tunable molar masses, compositions, functionalities, and architectures (homopolymers, statistical and block copolymers). The potential of these innovative catechol-containing (co)polymers was then explored for applications in energy storage (as active-material in lithium-ion half-cells) and environment (as protein fouling/antifouling coatings). [less ▲]

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See detailGiving an account of fictional discourse. Meinongian logics versus modal logics
Leclercq, Bruno ULiege

Conference (2017, August 29)

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See detailThe Economic Development Pole (EDP) approach in Niger: the case of the Niger-IFAD Program
Andres, Ludovic ULiege; Populin, Martha; Bodé, Sambo et al

Poster (2017, August 29)

Since 2012, the Niger-IFAD Programme uses a new non-administrative geographical intervention unit, the Economic Development Pole (EDP). The EDP is described as a space concentrating economic activities ... [more ▼]

Since 2012, the Niger-IFAD Programme uses a new non-administrative geographical intervention unit, the Economic Development Pole (EDP). The EDP is described as a space concentrating economic activities linked to the production and commercialization of the main agro-pastoral products of the neighbouring production basins. This poster aims to describe and analyze the concept of EDP, to show its first results when put into practice and to analyze its risks. [less ▲]

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See detailExperimental and theoretical investigation of SrFe12O19 nanopowder for permanent magnet application
Abraime, Brahim; Ait tamerd, Mohamed; Mahmoud, Abdelfattah ULiege et al

in Ceramics International (2017)

Strontium M-type hexagonal ferrites were synthesized at different calcination temperatures (800 °C, 1000 °C and 1100 °C) using sol-gel autocombustion method. Thermogravimetric analysis (TGA), X-ray ... [more ▼]

Strontium M-type hexagonal ferrites were synthesized at different calcination temperatures (800 °C, 1000 °C and 1100 °C) using sol-gel autocombustion method. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy (MS) and superconducting quantum interference device magnetometer (SQUID) techniques were used to characterize crystal structure, phase composition, morphology and magnetic properties. TGA gives T = 800 °C as beginning of suitable calcination. Hexaferrite structure of single phase is obtained according to XRD results for all samples with crystallite size between 28 nm and 35 nm. SEM images show the growth of grain size with increasing of annealing temperature. (BH)max is calculated based on SQUID results and shows an enhancement between T = 800 °C and T = 1000 °C of 25%. The magnetic properties observed at low temperature are explained and confirmed by ab-initio calculations [less ▲]

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See detailLes systèmes électoraux et leurs effets
Verjans, Pierre ULiege

Learning material (2017)

Le système politique belge fonctionne depuis plus d'un siècle sur le scrutin proportionnel. Quelles sont les conséquences des divers systèmes électoraux?

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See detailUniversité d'été du CIFEN - Atelier 2 :Tâches complexes dans les formations professionnalisantes
Francois, Nathalie ULiege; Simons, Germain ULiege

Conference (2017, August 25)

Introduction et synthèse de l'atelier consacré aux tâches complexes dans les sections professionnalisantes de différents niveaux d'enseignement en Fédération Wallonie Bruxelles.

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See detailPrésentation de la thématique de recherche et du programme de la journée
Simons, Germain ULiege

Conference (2017, August 25)

Dans cette introduction, G. Simons montre comment la notion de "tâche complexe" s'est construite progressivement en Communauté française de Belgique depuis le Décret "Missions". Ensuite il propose ... [more ▼]

Dans cette introduction, G. Simons montre comment la notion de "tâche complexe" s'est construite progressivement en Communauté française de Belgique depuis le Décret "Missions". Ensuite il propose différentes questions qui baliseront la réflexion tout au long de la journée. Enfin, il présente le programme du colloque et remercie toutes les personnes qui ont contribué à son organisation. [less ▲]

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See detailFragmentation index of DNA sperm in llama semen (Lama glama)
Cucho, Hernan; Ordonez, Cesar; Ampuero, Enrique et al

Poster (2017, August 25)

DNA fragmentation of spermatozoa is an important indicator of seminal quality and fertility. The quality of the genetic information contained in the DNA molecule transmitted by the spermatozoa is ... [more ▼]

DNA fragmentation of spermatozoa is an important indicator of seminal quality and fertility. The quality of the genetic information contained in the DNA molecule transmitted by the spermatozoa is important for the proper development of the embryo. In humans it has been shown that there is a significant correlation between sperm DNA damage and oocyte fertilization, embryo quality, development to blastocyst and embryo implantation. The objective of this study was to analyze the fragmentation of DNA sperm in llama semen collected by post-copulation vaginal aspiration. The collection of 4 llamas was performed on three occasions per animal. The volume, motility, concentration, vitality, sperm membrane functionality assessed with the Integrated Semen Analysis System - ISAS®. The DNA fragmentation index was tested with the Halomax system ®(Halotech company). Volume, motility, vitality and sperm concentration respectively were 1.3 ± 0.8 ml, 12.30 ± 2.02%; 64.69 ± 11.39% and 183.55 ± 28.48 x 106 spz/ml. The functionality of the sperm membrane was 64.95 ± 11.63% and sperm DNA fragmentation index 11.58 ± 13.25%. The values of these different parameters indicate the high quality of the collected semen. [less ▲]

See detailHigh-resolution reconstruction of 8.2 ka event recorded in Belgian Holocene speleothems
Allan, Mohammed ULiege; verhyden, sophie; Fagel, Nathalie ULiege

Scientific conference (2017, August 24)

Two abrupt shifts in d18O and trace element contents of a stalagmite from the northwestern European continent (southern Belgium) suggest that two cold anomalies occurred beginning at 8.4±0.04 and ending ... [more ▼]

Two abrupt shifts in d18O and trace element contents of a stalagmite from the northwestern European continent (southern Belgium) suggest that two cold anomalies occurred beginning at 8.4±0.04 and ending at 8.15±0.03, possibly reflecting climatic effects associated with the 8.2 ka event. The younger of the two anomalies lasted about 30 years, from 8.18 to 8.15±0.03 ka, with a maximum d18O amplitude of 1.4‰. Trace element (Sr, Ba and Mg) peaks coincide with this second drop of d18O. The anomaly initiation is marked by Sr, Ba and Mg concentration peaks suggesting drier conditions during the coldest years, consistent with previous research in the North Atlantic. The earlier anomaly in trace element, d18O records is associated with generally cold but wet conditions at 8.4 ka, lasted 50 years, and ended abruptly. The interval from 8.4 ka to 8.15 ka was less favorable for speleothem deposition, with denser speleothem calcite deposition and lower growth rate, consistent with a cold, dry climate. The clear recovery in both temperature and rainfall between after both anomalies (8.2 and 8.4 ka), suggests that these anomalies are distinct, and may represent two episodes of AMOC weaking related to the drainage of proglacial lakes Agassiz and Ojibway. [less ▲]

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See detailL'écrit et l'oral réflexifs : un tissage heuristique
Scheepers, Caroline ULiege

in Fischer, Carole; Gagnon, Roxane; De Piétro, Jean-François (Eds.) L'oral aujourd'hui : perspectives didactiques (2017)

La présente contribution envisage l’oral réflexif tel qu’il se décline dans les journaux des apprentissages. Dans plusieurs classes d’école primaire ou secondaire, en France, en Belgique, au Québec, au ... [more ▼]

La présente contribution envisage l’oral réflexif tel qu’il se décline dans les journaux des apprentissages. Dans plusieurs classes d’école primaire ou secondaire, en France, en Belgique, au Québec, au cours ou au terme de leur journée de classe, des élèves prennent la plume pour écrire dans un cahier à propos de leurs apprentissages, de leurs difficultés, de leurs incompréhensions, de leurs stratégies d’apprentissage, de leurs modes de résolution de problèmes, mais aussi à propos des relations interpersonnelles nouées à l’école, des tâches prescrites par l’enseignant ou de ses pratiques pédagogiques. Tout aussi inlassablement, les enseignants dialoguent avec les enfants en commentant, interrogeant, discutant les annotations des scripteurs dans leur cahier. Ils lisent et écrivent, ils réajustent les projets pédagogiques en fonction des textes lus. Au début de la journée, un enfant est invité à lire devant la classe le texte qu’il a rédigé la veille. Les pairs et l’enseignant écoutent le texte ainsi livré à tous, ils le commentent le cas échéant. On le voit, le dispositif du journal d’apprentissage associe étroitement oral et écrit réflexifs. Cette contribution s’attachera à dégager l’articulation du scriptural et de l’oral au cœur et autour du journal des apprentissages. Nous tenterons d’abord de mieux cerner le genre « journal des apprentissages » sur le plan des pratiques langagières orales et scripturales qu’il sollicite et contribue à construire chez l’élève. Nous verrons si une délimitation nette peut être tracée entre les unes et les autres. Ensuite, nous analyserons les annotations des scripteurs consacrées aux tâches orales réalisées en classe, ce qui permettra d’identifier comment l’oral est mobilisé ou enseigné dans les classes de l’échantillon, mais aussi d’analyser la réception des activités orales auprès des apprenants. Notre corpus est international et compte près de deux-cents journaux tenus par des enfants du primaire et des adolescents du secondaire, dans des contextes contrastés. [less ▲]

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See detailSplit-Band Interferometry-Assisted Phase Unwrapping for the Phase Ambiguities Correction
Libert, Ludivine ULiege; De Rauw, Dominique ULiege; d'Oreye, Nicolas et al

in Remote Sensing (2017), 9(9),

Split-Band Interferometry (SBInSAR) exploits the large range bandwidth of the new generation of synthetic aperture radar (SAR) sensors to process images at subrange bandwidth. Its application to an ... [more ▼]

Split-Band Interferometry (SBInSAR) exploits the large range bandwidth of the new generation of synthetic aperture radar (SAR) sensors to process images at subrange bandwidth. Its application to an interferometric pair leads to several lower resolution interferograms of the same scene with slightly shifted central frequencies. When SBInSAR is applied to frequency-persistent scatterers, the linear trend of the phase through the stack of interferograms can be used to perform absolute and spatially independent phase unwrapping. While the height computation has been the main concern of studies on SBInSAR so far, we propose instead to use it to assist conventional phase unwrapping. During phase unwrapping, phase ambiguities are introduced when parts of the interferogram are separately unwrapped. The proposed method reduces the phase ambiguities so that the phase can be connected between separately unwrapped regions. The approach is tested on a pair of TerraSAR-X spotlight images of Copahue volcano, Argentina. In this framework, we propose two new criteria for the frequency-persistent scatterers detection, based respectively on the standard deviation of the slope of the linear regression and on the phase variance stability, and we compare them to the multifrequency phase error. Both new criteria appear to be more suited to our approach than the multifrequency phase error. We validate the SBInSAR-assisted phase unwrapping method by artificially splitting a continuous phase region into disconnected subzones. Despite the decorrelation and the steep topography affecting the volcanic test region, the expected phase ambiguities are successfully recovered whatever the chosen criterion to detect the frequency-persistent scatterers. Comparing the aspect ratio of the distributions of the computed phase ambiguities, the analysis shows that the phase variance stability is the most efficient criterion to select stable targets and the slope standard deviation gives satisfactory results. [less ▲]

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See detailVideo and camera traps to investigate animal ecophysiology and enhance wildlife management: case study on bees and elephants interactions in Gabon.
Ngama, Steeve ULiege; Bindelle, Jérôme ULiege; Vermeulen, Cédric ULiege

Conference (2017, August 23)

Crops are often sources of conflict between humans and wildlife. Wildlife damage to crops can drastically reduce income, amplifying poverty and creating a negative perception of wild animal conservation ... [more ▼]

Crops are often sources of conflict between humans and wildlife. Wildlife damage to crops can drastically reduce income, amplifying poverty and creating a negative perception of wild animal conservation among rural people. In this context, crop-raiding animals like elephants quickly become “problem animals”. To deter elephants from raiding crops beehives have been successfully employed in East Africa while providing honey for the farmers. Whether such a technique could work on forest elephants (Loxodonta Africana cyclotis) in Central Africa is still unknown. An ecophysiology-based trial consisting on bees and elephants interactions assessment was conducted in Gabon. It aimed to evaluate whether the presence of Apis mellifera adansonii, the African honey bee species present in Central Africa, deters forest elephants from feeding on experimental wild fruit trees. We suspected that bee physiology matters on bee defensive behavior and monitoring it through measuring bee activities can help better understand bees and elephants interactions. For this purpose video cameras were used to record activities of bees in fourteen beehives hung on seven wild trees (4 Irvingia gabonensis and 3 Sacoglottis gabonensis trees) each equipped with a camera trap to record elephants feeding behaviors on those trees. This experimental apparatus was monitored during 70 consecutive weeks from 2012 to 2013. We captured 8151 photos representing 4h31min42s of time spent by elephants at experimental trees and more than 75 videos of bees activities from where we extracted genuine results. Our results show a significant correlation between the effectiveness of beehives as deterrents of elephants and bee activity. Although elephant disturbance of hives does not inhibit honey production, there is a tradeoff between deterrence and the quantity of honey produced. More interestingly, to best achieve the dual goals of deterring elephants and producing honey colonies must maintain an optimum activity level of 40 to 60 bee movements per minute. Thus Apis mellifera adansonii bees can effectively deter elephants but beehives must be actively managed to maintain bees’ colonies at the optimum activity level. [less ▲]

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See detailPreservation protocol for dimethylsulfoniopropionate and dimethylsulfoxide analysis in plant material of the Mediterranean seagrass Posidonia oceanica, and re-evaluation of dimethylsulfoniopropionate leaf content
Borges, Alberto ULiege; Champenois, Willy ULiege

in Aquatic Botany (2017), 143C

We tested three treatments to preserve Posidonia oceanica leaves for the analysis of dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO): oven dried at 60 °C for 24 h, frozen at −20 °C, and ... [more ▼]

We tested three treatments to preserve Posidonia oceanica leaves for the analysis of dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO): oven dried at 60 °C for 24 h, frozen at −20 °C, and frozen-in-ice and kept at −20 °C. The DMSP content was analyzed by proxy as dimethylsulfide (DMS) by gas chromatography after alkaline cleavage at room-temperature. The DMSP leaf content of P. oceanica in samples that were oven dried at 60 °C for 24 h, then stored at room temperature decreased by 87% over 80 days of storage and then remained stable for about 88 additional days compared to the control. The DMSO leaf content of P. oceanica in samples that were oven dried increased nine-fold after 198 days of storage following drying compared to the control. Both the DMSP and DMSO leaf content of P. oceanica remained stable for 198 days compared to the control with frozen and frozen-in-ice treatments, which we both recommend as adequate protocols to preserve P. oceanica tissues for DMS(P,O) analysis. The annual average DMSP leaf content of P. oceanica at 10 m in the Bay of Calvi (Corsica, France) was 205 ± 58 μmol g−1 (fresh weight) based on samples preserved frozen, two orders of magnitude higher than the value we previously reported based on samples that were oven dried. The newly determined DMSP leaf content allows ranking P. oceanica as the highest DMSP producer reported to date among marine and inter-tidal autotrophs. [less ▲]

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See detailVariation of tree allometry and aboveground biomass in central African forests
Loubota Panzou, Grâce Jopaul ULiege; Ligot, Gauthier ULiege; Bastin, Jean-François et al

Conference (2017, August 23)

Quantifying the biomass and carbon stocks contained in tropical forests has become an international priority for the implementation of the REDD+ initiative. Many techniques exist to estimate forest ... [more ▼]

Quantifying the biomass and carbon stocks contained in tropical forests has become an international priority for the implementation of the REDD+ initiative. Many techniques exist to estimate forest biomass at different spatial scales, but all ultimately rely on allometric equations calibrated on destructive measurements of individual tree biomass, in order to convert forest inventory data into biomass estimates. For many tropical forest ecosystems, that are structurally complex and species rich, these allometric equations have not yet been developed and general allometric equations are being used instead, with possibly local adjustment of tree allometry with non-destructive data. Variation in height-diameter allometry and in crown-diameter allometry across forest types and environmental conditions have been demonstrated to be of extreme importance for the estimation of biomass and carbon stocks in tropical forests, but yet poorly explored in central Africa. In this study we aimed to determine the variation in tree height-diameter and crown-diameter allometries across central African forests and the consequences for biomass and carbon stocks. Tree allometry data were collected in two of semi-deciduous forest sites in northern Republic of Congo that have vastly different substrate and soils (clay soils on quartzite and sandy soils on sandstone plateau), and forest communities, but similar rainfall regimes. These data will be analyzed to test two hypotheses: (i) tree allometry strongly varies across forest types with contrasted environmental conditions (and specifically soils), and (ii) both allometry and forest structure contributed to the greater biomass of the site on rich soil (quartzite substrate). Our newly collected data for two sites in northern Congo will be confronted to existing allometry and inventory data available elsewhere in the Congo basin to get a broader picture of allometric variations and its consequences for the estimation of biomass and carbon stocks. [less ▲]

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